Epidemiologic studies are conducted to identify life-style and environmental risk factors for cancer and to investigate their interrelationships with genetic determinants of these diseases. Case-control studies of cancers of the bladder, prostate, pancreas, esophagus, stomach, lung, brain, and head and neck, as well as non-Hodgkins lymphoma and multiple myeloma, are in progress. A large case-control study of bladder cancer is progressing in Spain to identify occupational bladder carcinogens and to evaluate non-occupational exposures including cigarette smoking (black vs. blond tobacco), phenacetin-containing analgesics, dietary factors, and urination frequency and pH. Genetic susceptibility markers also will be evaluated in relation to bladder cancer risk, as well as their interaction with epidemiologic risk factors. A large multi-center investigation is examining risk factors for malignant neoplasms among subjects being screened for cancers of the prostate, lung, colon, rectum, and ovaries. A large case-control study of bladder cancer in New England is underway to determine the reasons for the persistently elevated bladder cancer mortality and incidence in the northeastern United States. In a case-control study of pancreatic cancer conducted to determine the reasons for the black excess in risk of the disease, established risk factors (mainly cigarette smoking and diabetes mellitus) explained almost the entire black/white disparity in incidence among men. Among women, however, other factors appear to contribute to the racial disparity, notably moderate/heavy alcohol consumption and elevated body mass index. In Puerto Rico, results of a population-based case-control study of oral cancer suggested that alcohol concentration is a risk factor for oral cancer independent of the total quantity of alcohol consumed. Risks associated with combined exposure to tobacco were also more pronounced when subjects drank liquor straight. In Shanghai, a multi-center case-control study of colon cancer indicated that diets high in fruit and antioxidant vitamins that are common in plant foods reduce the risk of colon cancer, whereas diets high in red meat, eggs, and preserved foods increase colon cancer risk. In the United States, a multi-center case-control study of esophageal and gastric cancers indicated that a few known risk factors account for a majority of esophageal and gastric cancers. Results suggested that the incidence of these cancers may be decreased by reducing the prevalence of smoking, gastroesophageal reflux, and being overweight and by increasing the consumption of fruits and vegetables. Findings from a multi-center case-control study of prostate cancer in American blacks and whites suggested that greater height may be associated with better survival from prostate cancer.